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Brand new glow plugs, engine won’t start

Discussion in 'Engine, Drivetrain, Fuel and Exhaust' started by William Mazza, Feb 27, 2020.

  1. William Mazza

    William Mazza New Member

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    Your Mercedes:
    1987 190d 2.5l turbo diesel
    I just replaced all 5 glow plugs with Bosch glow plugs on my 2.5l turbo diesel and after putting everything back together my glow plug light won’t come on the dash, and the engine will not start. Any advice?
     
  2. Mark A

    Mark A Senior Member

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    Aberdeen
    Your Mercedes:
    08 ML-420CDI, 58 ML-320CDI, 66 CLS-220d
    Fuse / relay??

    check to see if you are getting a voltage at the plugs.
     
  3. onefortheroad

    onefortheroad Senior Member

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    Your Mercedes:
    c250 amg premium 2 door coupe.
    Are they the same voltage as the old plugs
     
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  4. OP
    William Mazza

    William Mazza New Member

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    Your Mercedes:
    1987 190d 2.5l turbo diesel
    Will be checking today will let you guys know, thank you!
     
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  5. OP
    William Mazza

    William Mazza New Member

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    Your Mercedes:
    1987 190d 2.5l turbo diesel
    I am checking the relay now and I do not see a fuse
     

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  6. M80

    M80 Senior Member

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    Your Mercedes:
    Vito 115 Lwb Dualiner.
    Are these engines so dependant on glow plugs? Could it be something else?
    Maybe use some easy start to eliminate another cause.
     
  7. js190d

    js190d Senior Member

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    Location:
    newcastle
    Your Mercedes:
    1991 w201 190d 2.5/ 2002 s210 320cdi avantgarde
    Hi William, that is a rare car. Why did you change the glow plugs?

    How was it working prior to you changing the plugs?

    The fuse is usually a metallic strip inside the glow plug relay.

    Although i have just gone and looked at my 190d 2.5's glow plug relay and it looks exactly the same as yours so no metallic strip fuse on mine either.Also no fuse assigned to the glow plug relay in the fusebox. Maybe try bridging the gap between the 2 contact points on left hand side the relay (as pictured).

    The glow plug light should come on indicating pre heating is it not doing this? The light will stay on after start up if 1 or more glow plugs are not working.

    This may be some help...

    https://www.dieselgiant.com/glowplugrepair.htm
     
    Last edited: Feb 27, 2020
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  8. John Laidlaw

    John Laidlaw Senior Member

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    Your Mercedes:
    UnMercs BMW i8 Volvo XC90
    AFAIK The ‘fuse’ is inbuilt so you may have to replace the relay (or butcher it)
     
  9. OP
    William Mazza

    William Mazza New Member

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    Your Mercedes:
    1987 190d 2.5l turbo diesel
    The engine was running very rough at idle so I began checking everything causing me to find a bad glow plug on the 5th cylinder
     
  10. js190d

    js190d Senior Member

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    Your Mercedes:
    1991 w201 190d 2.5/ 2002 s210 320cdi avantgarde
    And after it warmed up a bit did it run smoothly and start up ok?

    If you had 4 good glowplugs i would expect your engine to fire up easily from cold.

    Were you getting the pre heating light on prior to start up (and after start up if no5 GP was bad)

    Is this a car that has not been in use for some time?
     
  11. OP
    William Mazza

    William Mazza New Member

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    Your Mercedes:
    1987 190d 2.5l turbo diesel
    The glow plugs light did come on in the prior months to owning it, when the light stopped working I proceeded to check the glow plugs, finding no5. The previous owners said that they would start the car time to time but never really used that much
     
  12. js190d

    js190d Senior Member

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    Your Mercedes:
    1991 w201 190d 2.5/ 2002 s210 320cdi avantgarde
    Sounds like you need a new GP relay.

    May be an idea if the car has been unused for a while to change all the fuel filters (metal canister, in line fuel filter & and even the in tank strainer) as part of a service.

    With working glow plugs and a strong battery an OM602 should fire up pretty much instantly (assuming compression is good).

    Other common issues are leaking fuel delivery seals on the injection pump (cost about £15 from Mercedes and not difficult to replace) which would compromise start up.
     
  13. OP
    William Mazza

    William Mazza New Member

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    Your Mercedes:
    1987 190d 2.5l turbo diesel
    I Changed all fuel filters and replaced the battery when purchasing this vehicle
     
  14. js190d

    js190d Senior Member

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    Your Mercedes:
    1991 w201 190d 2.5/ 2002 s210 320cdi avantgarde
    So has it been started since changing all the fuel filters.
     
  15. OP
    William Mazza

    William Mazza New Member

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    Your Mercedes:
    1987 190d 2.5l turbo diesel
    Yes it has it had been running with good compression until the glow plug went bad I am noticing now that the replacement glow plugs from Bosch are 11v and the original plugs are 11.5v idk if that will make a difference
     
  16. js190d

    js190d Senior Member

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    Your Mercedes:
    1991 w201 190d 2.5/ 2002 s210 320cdi avantgarde
    The ones in mine are Beru 11.5V.

    You could always try putting the 4 good old ones back in and seeing if that makes the GP relay work again.
     
  17. mattkh

    mattkh Senior Member

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    Your Mercedes:
    W168 1999 1.6
    Sounds like a loose electrical connection to the glow plugs. Put up a picture of that side of the engine.
     
  18. OP
    William Mazza

    William Mazza New Member

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    Your Mercedes:
    1987 190d 2.5l turbo diesel
    So I went to an auto parts store and showed them one new and one old gp they looked up the part number and apparently, the other store I got them from messed up and gave me the wrong gps. I’m hoping all I need is the correct gps for this to work, they come in tomorrow morning. I will let everyone know asap
     
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  19. davemercedes

    davemercedes Senior Member

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    Your Mercedes:
    2007 Merc 220 CDi Est Auto Av
    Well done (I hope) so fingers Xd... :)
     
  20. js190d

    js190d Senior Member

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    Your Mercedes:
    1991 w201 190d 2.5/ 2002 s210 320cdi avantgarde
    I don't suppose we could have some pics of your car? Pretty much unheard of in the UK.
     

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